"There is not a woman in the world the possession of whom is as precious as that of the truths which she reveals to us by causing us to suffer" - Marcel Proust

The possession of whom...

Remember, it was a different time and a different world when the quote came into existence. Even then, I believe it was meant figuratively rather than literally. It can easily be interpreted as referring to the possession of her love, which can only be possessed if she freely gives it. That's how I choose to look at it. YMMV.